SPOKAN — Three Republican U.S. House members are criticizing Democratic Sen. Patty Murray and other lawmakers for opposing their legislation that would prevent the breaching of four dams on the Snake River to restore endangered salmon runs.

The three Republicans from the state of Washington support a bipartisan bill that seeks to maintain existing dam operations until at least 2022.

Murray and two Democratic House members from the Seattle area are pushing an environmental study to examine alternatives for salmon recovery, including breaching one or more of the dams to aid fish migration to and from the Pacific Ocean.

“It’s unthinkable that Seattle Democrats are putting politics over science when it comes to improving fish recovery efforts,” Reps. Dan Newhouse, Cathy McMorris Rodgers and Jaime Herrera Beutler said in a release this week. “Millions of dollars have been spent studying these dams and improvements have been made to improve fish survival rates.”

The skirmish is the latest in a decades-long battle that pits environmentalists against users of the Columbia-Snake river system.

Fish advocates blame the four dams, built in the 1960s and 1970s, with decimating iconic salmon runs in the river system. But supporters of the dams point to the benefits of hydropower and navigation provided by the dams, and say fish ladders and other methods of transporting salmon past the dams are helping restore the runs.

Murray sent a letter on Tuesday to Senate and House leaders criticizing Newhouse’s bill that supports existing dam operations.

The letter, also signed by Democratic U.S. Reps. Adam Smith and Pramila Jayapal, contends Newhouse’s bill would circumvent a process to consider all uses of the river system. Managers must consider salmon recovery, fisheries, irrigation, navigation, power generation, flood protection and recreation, they said.

“The Columbia and Snake River system is essential to the Pacific Northwest’s culture, environment and economy,” the Democrats said.

In 2016, U.S. District Court Judge Michael Simon of Portland, Oregon, ordered the new environmental review and a new federal biological opinion. The current biological opinion, created by federal agencies, states and tribes to protect salmon while operating the dams, does not do enough to rebuild endangered fish populations, the judge ruled.

The study is intended to evaluate the costs and benefits of multiple alternatives, ranging from no changes to removing all four dams. There have been 18 public meetings in the Pacific Northwest and more than 412,000 public comments have been submitted, according to the letter.

Simon also has ordered more water to be spilled over dams starting this spring, which is intended to help out-migrating juvenile salmon swim more quickly and safely to the ocean. Some critics of the decision say the spill would do little to help fish and could create high gas levels in the water that can harm juvenile fish.

The spilled water would otherwise be used for power generation, and will cost Washington residents $40 million in higher electric rates this year, Newhouse said.

“They claim to support clean renewable energy, while simultaneously working to destroy hydropower, Washington state’s largest source of carbon-neutral, clean energy,” Newhouse said. “Breaching the dams … should not even be an option.”